In recent years, the production of propylene oxide from propylene using hydrogen peroxide as an oxidant and a titanium-containing zeolite as a zeolite as a catalyst has been proposed. Methanol is a particularly preferred reaction solvent for such purposes, as it tends to promote high catalyst activity and selectivity. Epoxidation processes of this type are described, for example, in U.S. Pat. Nos. 5,591,875, 4,833,260, 5,621,122, 5,646,314, and 4,824,976, EP Pub. No. 0732327, and Clerici et al., J. Catalysis 129, 159-167 (1991), the teachings of which are incorporated herein by reference in their entirety. Although such processes are capable of providing exceptionally high selectivity to propylene oxide, minor quantities of certain by-products such as acetaldehyde are inevitably formed. Since a satisfactory propylene oxide for commercial purposes should contain less than 100 ppm, and preferably less than 20 ppm, acetaldehyde, the development of methods for separating substantially all of the acetaldehyde by-product from such reaction mixtures is necessary. In addition, epoxidation processes of this type form water as a co-product with the water being derived from the hydrogen peroxide oxidant. Depending upon the method used to generate the hydrogen peroxide to be used in the epoxidation reaction, water may also be present in the feed to the reactor. While epoxidation processes catalyzed by titanium-containing zeolites are remarkably tolerant of water, it will be necessary for most commercial purposes to obtain propylene oxide in substantially anhydrous form. An efficient method of removing water from the propylene oxide produced by such an epoxidation process therefore is needed.